Jun 5, 2011 #1 carlosgw Mechanical Joined Oct 3, 2004 Messages 167 Location US I mean the inner liner for typical flex duct used for connections to diffusers.
Jun 6, 2011 #2 EnergyProfessional Mechanical Joined Jan 20, 2010 Messages 1,279 Location US depending on quality, it gets brittle sooner or later. they also can get damaged easily. Upvote 0 Downvote
Jun 9, 2011 #3 willard3 Mechanical Joined Jan 14, 2006 Messages 1,437 Location US All materials change with age, including polymers/plastics. Flex duct is fragile. Upvote 0 Downvote